Community Forums

swaff54 · 10-22-2024, 11:12 AM

So, I've had both AC capacitors die in the last few months. When the first one on the front AC died, we were at the Escapees Escapade in Rock Springs, WY. There was a mobile tech that had a "used" capacitor which he installed. He only charged me labor. It's been working fine.

The rear AC started acting up a week or so ago. I engaged a different mobile tech and they had to order a new capacitor. It was installed today and seems to be OK.

I'm thinking that I want to go ahead and order a spare or 2 for the future. The capacitor that was in the rear unit was a 55/15. The replacement was a 55/5. I have no idea what the used unit installed in the front AC is.

Question is, what's the difference between 55/15 vs 55/5. Which should I order for the spare.

As always, thanks.

Suburbazine · 10-22-2024, 11:50 AM

You can go bigger, never go smaller. 55 is the amp rating for starting the compressor, 15 is the amp rating for the fan motor. A 55/5 will be ok for the compressor and really bad for the fan motor. The X/X spec basically just means it's two capacitors in one with a common terminal.

Bigger ones will just give you a more effective kick, but they are bulkier and cost more. You can also run two separate caps, one for the compressor and one for the fan, with the obvious cost of space. Typical minimum is to spec for 3x the running amperage, but over spec will give you some extra safety margin if it will fit in the box.

terrylane · 10-22-2024, 11:50 AM

When you have two systems of the same age and similar use, you might consider replacing the capacitors on both systems when one fails. Most of the labor cost is getting out there and on the roof, actually doing the work is usually trivial.

If buying new parts, you should get something with the same specs the factory installed. As a short term temporary measure something else may work, but the factory usually knows best.

SafariBen · 10-22-2024, 03:26 PM

As stated the first number is "herm" for hermetically sealed compressor, the second number is the fan, so the 55/5 has less capacitance than the 55/15 for the fan, but the same for the compressor. Microfarads is the rating, not that it matters to us.

Are you sure the one was 55/15? 15 is kind of high for a fan, not sure I've ever seen that.

Suburbazine · 10-22-2024, 04:24 PM

Quote:

Originally Posted by SafariBen

Are you sure the one was 55/15? 15 is kind of high for a fan, not sure I've ever seen that.

The Dometic fan is rated at 5 amps.

swaff54 · 10-22-2024, 06:20 PM

The removed capacitor is definitely a 55/15. My Ventana was optioned with Dometic 15000 units as opposed to the standard 13500 units.

I had a conversation with the lead tech at the mobile tech company and after providing him the details, he agreed that they had installed an incorrect capacitor for my unit. He did advise not to run that unit until the capacitor is replaced.

A new capacitor is on order and will be installed at no cost to me.

I'm happy with the resolution.

richpatty · 10-23-2024, 07:15 AM

What were the symptoms that you knew it as the capacitor?

swaff54 · 10-23-2024, 07:19 AM

Quote:

Originally Posted by richpatty

What were the symptoms that you knew it as the capacitor?

Low air flow and lack of cooling was what led me to having it checked out. The first time, I was really afraid of an expensive repair. The tech confirmed the capacitor failure. The capacitor is a relatively cheap part.

richpatty · 10-23-2024, 08:18 AM

Quote:

Originally Posted by swaff54

Low air flow and lack of cooling was what led me to having it checked out. The first time, I was really afraid of an expensive repair. The tech confirmed the capacitor failure. The capacitor is a relatively cheap part.

Thanks. As one of my AC units has stopped working…. The fans blow and the compressor seems to run (draws 12-14 amps) but does not blow hot or cold…. So I think it it a freon issue. I wanted it to be a capacitor, but can’t see how it can be.
Thanks.

Country Road · 10-23-2024, 08:44 AM

Quote:

Originally Posted by swaff54

The removed capacitor is definitely a 55/15. My Ventana was optioned with Dometic 15000 units as opposed to the standard 13500 units.

I had a conversation with the lead tech at the mobile tech company and after providing him the details, he agreed that they had installed an incorrect capacitor for my unit. He did advise not to run that unit until the capacitor is replaced.

A new capacitor is on order and will be installed at no cost to me.

I'm happy with the resolution.

Well, I don’t know about the decision to use a 55/5. That would put the fan amps at the top of the capacitors amp limit. In a perfect world, it would be fine. But if anything comes into play like a weakened fan motor or lower than normal voltage, it could create an additional fan problem.

I just replaced 2 of my 3 capacitors and they took care of my problem. I also put on a SoftStartRV and it’s wonderful.

By the way, both of my replaced capacitors were 55/15. Good luck.

terrylane · 10-23-2024, 10:57 AM

Just an FYI...from Trane:

"An AC capacitor provides the initial jolt of electricity your air conditioner’s motors need to run successfully. It stores electricity and sends it to your system’s motors in powerful bursts that get your unit revved up as it starts the cooling cycle. Once your AC is up and running, the capacitor reduces its energy output, but still supplies a steady current of power until the cycle finishes.

AC capacitors are measured in voltage and microfarads. Voltage shows how much electrical current is moving through the capacitor. The more voltage in your capacitor, the faster the electrical current moves throughout it. Microfarads, meanwhile, describe how much electrical current the capacitor can store. Most capacitors range from 5 MFD (microfarads) to 80 MFD."

MarkMaxPayne · 10-23-2024, 11:15 AM

Not to be contrary, but I've always replaced with a soft start device. I know they cost more, but I've always enjoyed the results.

Best,
-Mark

SafariBen · 10-23-2024, 12:53 PM

Quote:

Originally Posted by richpatty

Thanks. As one of my AC units has stopped working…. The fans blow and the compressor seems to run (draws 12-14 amps) but does not blow hot or cold…. So I think it it a freon issue. I wanted it to be a capacitor, but can’t see how it can be.
Thanks.

Agree, you could remove the cover and see if the coils get warm and cool when it turns on, there's a remote possibility it's an air flow problem still. Also possible that it's a physical internal problem, like valves, etc. Most likely it's low freon though. Usually a system with no freon will run with less amps than the identical one with a proper charge. So if a working one is drawing 14 amps to start and drops to 12 amps running, then the bad one will start at 12 and quickly drop to 11, or something like that.

richpatty · 10-23-2024, 05:48 PM

Quote:

Originally Posted by SafariBen

Agree, you could remove the cover and see if the coils get warm and cool when it turns on, there's a remote possibility it's an air flow problem still. Also possible that it's a physical internal problem, like valves, etc. Most likely it's low freon though. Usually a system with no freon will run with less amps than the identical one with a proper charge. So if a working one is drawing 14 amps to start and drops to 12 amps running, then the bad one will start at 12 and quickly drop to 11, or something like that.

Interesting. Thanks
I currently have an appt to replace it at NIRVC in December. But maybe I can take a look before.